Organic semiconductors are being developed for a number of electronic applications of different types. The structure of organic electroluminescent devices (OLEDs), in which these organic semiconductors are employed as functional materials, is described, for example, in U.S. Pat. Nos. 4,539,507, 5,151,629, EP 0676461 and WO 98/27136. However, further improvements are still desirable for use of these devices for high-quality and long-lived displays. Thus, in particular, the lifetime and efficiency of blue-emitting organic electroluminescent devices currently still represent a problem, for which there is still a need for improvement. It is furthermore necessary for the compounds to have high thermal stability and a high glass transition temperature and to be sublimable without decomposition. A high glass transition temperature is essential for achieving long lifetimes, in particular for applications at elevated temperature.
For fluorescent OLEDs, use is made in accordance with the prior art of, in particular, condensed aromatic compounds, in particular anthracene derivatives, as host materials, especially for blue-emitting electroluminescent devices, for example 9,10-bis(2-naphthyl)anthracene (U.S. Pat. No. 5,935,721). WO 03/095445 and CN 1362464 disclose 9,10-bis(1-naphthyl)anthracene derivatives for use in OLEDs. Further anthracene derivatives are disclosed in WO 01/076323, WO 01/021729, WO 04/013073, WO 04/018588, WO 03/087023 or WO 04/018587. Host materials based on aryl-substituted pyrenes and chrysenes are disclosed in WO 04/016575. Host materials based on benzanthracene derivatives are disclosed in WO 08/145239. For high-quality applications, it is desirable to have improved host materials available.
Prior art which can be mentioned in the case of blue-emitting compounds is the use of arylvinylamines (for example WO 04/013073, WO 04/016575, WO 04/018587). However, these compounds are often unstable under thermal load and cannot be evaporated without decomposition, which requires high technical complexity for OLED production and thus represents an industrial disadvantage. For high-quality applications, it is therefore desirable to have improved emitters available, particularly with respect to device and sublimation stability and emission colour.
Thus, there continues to be a demand for improved materials, in particular host materials for fluorescent emitters, especially for blue- and green-fluorescent emitters, and fluorescent materials which are thermally stable, which result in good efficiencies and at the same time in long lifetimes in organic electronic devices, which result in reproducible results during production and operation of the device and which are readily accessible synthetically. Further improvements are also necessary in the case of hole- and electron-transport materials.